The development of higher-order crystalline structure induced by uniaxial elongation with constant Hencky strain rates epsilon(0) was investigated in the temperature range of 110-140 degrees C on supercooled liquid of a metallocene-catalyzed syndiotactic polystyrene (s-PS) via elongational flow opto-rheometry (EFOR), temperature-modulated differential scanning calorimetry, Rayleigh scattering, and polarized Fourier transform infrared spectroscopy. In the elongation at 110 degrees C where spherulite growth was neglected, chain-segment orientation along the flow preceded and flow-induced crystallization took place rather suddenly at a Hencky strain of epsilon(t) (= epsilon(ot)) approximate to 1.2 with the crystalline lamellae irregularly growing transverse to the oriented chains. On the other hand, at 130 degrees C where spherulite growth was rapid, strain-induced hardening due to the spherulite growth was observed in the early stage, and transformation of the spherulites into rodlike morphology followed, accompanying the increasing of birefringence. At 140 degrees C elongation with a low strain rate of epsilon(0) = 0.01 s(-1), stable spherulites were formed in the early stage, and the subsequent growth of the spherulites dominated the elongation behavior. However, at 140 degrees C elongation with high epsilon(0) (greater than or equal to 0.1 s(-1)), formed spherulites were appreciably deformed along the flow direction. Thus, the features of the flow-induced structure development were governed by the dimensionless strain rate that was the ratio of epsilon(0) to the spherulite growth rate under the quiescent state. For some semicrystalline polymers, the critical value of the dimensionless strain rate, below/above which the spherulite growth/oriented crystalline formation dominate, increases in order of the decreasing spherulite growth rate, i.e., s-PS, poly(ethylene terephthalate), and poly(ethylene naphthalate).